In the related art, there is a microscope device that has a mounting device that is provided with a plurality of objective lenses in an attachable/detachable manner and that can selectively place these objective lenses in an observation optical path of the microscope (for example, see Patent Literature 1). The microscope device disclosed in Patent Literature 1 is provided with a mounting device that has a first holding member that holds a first objective lens; a second holding member that holds a second objective lens having a shorter working distance than the first objective lens; a raising mechanism that moves the second objective lens in an optical axis direction; and an adjusting mechanism that adjusts the position of the second objective lens in the optical axis direction moved by the raising mechanism.
With this microscope device disclosed in Patent Literature 1, a state in which the first objective lens having a longer working distance is placed in the observation optical path of the microscope is used as a reference, and the first objective lens is switched to the second objective lens while maintaining parfocal distances therefor by moving the second objective lens in the optical axis direction with the raising mechanism and by adjusting the position to which the second objective lens is moved with the adjusting mechanism.